1. Field of the Invention
The present invention relates to a closure suitable for use with flexible bags and particularly disposable bags formed therewith. These bags include sandwich bags made out of polyethylene film as well as disposable trash and garbage bags made from the same and similar plastic materials. Related applications assigned to the same assignee as this application include the following co-pending applications: "Adhesive Channel Closure for Flexible Bags", Ser. No. 335,798; "Laminated Pressure Sensitive Adhesive Systems for Use in Plastic Bags", Ser. No. 335,799, U.S. Pat. No. 4,415,087 ; "Adhesive Bag Closure that Opens Easily by Hand But Resists Opening by Contents", Ser. No. 335,800; "Manufacturing Process for Channel Seal", Ser. No. 365,814, U.S. Pat. No. 4,392,897; and "Protective Strip for Z-Fold Bag Closures", Ser. No. 335,955, U.S. Pat. No. 4,410,130.
2. Brief Description of the Prior Art
Bags with various closure arrangements have been used to hold sandwiches, garbage, and for other household uses. These bags usually are comprised of a bag body and some type of closure arrangement. The most common closure arrangement for disposable bags like these has been a separate device like a "twister" which is applied to the bag by the user. Previous attempts at constructing bags with acceptable integral closure arrangements have included the so-called profile bags where the closure comprises one or more sets of mating channels. Each channel may be formed as an integral part of the bag or fabricated as a separate piece and attached to the bag. One example of a profile closure is found in Reissue Pat. No. 28,969 to Natito. Other examples of profile bags include U.S. Pat. No. 3,226,787 to Ausnit and U.S. Pat. No. 3,060,985. As seen in U.S. Pat. No. 4,186,786 to Kirkpatrick, colored channels have been used to allow the user to more easily detect complete occlusion of profile bag openings. In order to achieve satisfactory use of profile bag closures, however, the mating members must fit properly and be aligned correctly. It may take several attempts at closing the bag before proper registration of the mating members is finally achieved. Bags with profile closures also tend to be an expensive choice for uses which do not require the containment of liquids.
Other types of integral bag closures use one or more adhesive strips. Problems with such adhesive closures include weak shear strength because the exposed adhesive for a strip must be selected to be weak enough so that it does not undesirably stick to other bags while on a roll or in a box.
An attempt to combine a profile closure with an adhesive may be seen in U.S. Pat. No. 3,339,606 to Kugler. The releasable closure in the Kugler patent comprises a tongue on one member and a groove on the other member where the tongue is of a thickness less than the width of the groove and wherein a releasable pressure sensitive adhesive is provided to keep the tongue within the groove. This structure, however, still requires registration of mating channels. Attempts to protect the adhesive strip until the bag is used may be seen in U.S. Pat. No. 3,420,433 to Bostwick and U.S. Pat. No. 3,990,627 to Olson (and assigned to the same assignee as this application). It is difficult, however, to find an adhesive which is easy to apply, which is strong enough to form an effective seal upon closure, but which does not cause undesirable problems by sticking to other bags or miscellaneous surfaces.
Other types of closures, such as zippers and Velcro.TM. strips have, on occasion, been incorporated into reusable bags as closures. However, the costs of manufacturing and attaching these types of closures to film bag bodies virtually eliminates them as commercially viable candidates for use in disposable thin film plastic bags.
Thus, it is an object of the present invention to provide a bag having a nonadhesive closure. It is a further object of this invention to provide bags for use in a variety of applications in which the closure is not easily unsealed. It is yet another object of this invention to provide a bag having a closure seal wherein the closure seal does not have to be in exact registration to effect closure. It is a further object of this invention to provide a flexible bag with an openable and resealable closure. It is another object of this invention to provide a flexible bag with a resealable closure which exhibits good shear or peel strength. It is yet another object to provide a closure for disposable, thin film plastic bags which can be integrally formed into the bag. It is yet another object of the invention to provide an inexpensive integral closure for disposable, thin film plastic bags. These and other objects of the invention will be apparent from the following description.